1. Field of the Invention
The present invention relates to a system and method for providing a service in a communication system. More particularly, the present invention relates to a system and method for providing an emergency service in a communication system.
2. Description of the Related Art
A next-generation communication system is being developed to provide various high-speed, high-capacity services to Mobile Stations (MSs). Examples of the next-generation communication system include an Institute of Electrical and Electronics Engineers (IEEE) 802.16 communication system and a Mobile Worldwide Interoperability for Microwave Access (WiMAX) communication system. Here, the Mobile WiMAX communication system is based on the IEEE 802.16 communication system, and the IEEE 802.16 communication system is based on an IEEE 802.16 standard.
Next, an emergency service proposed for a conventional IEEE 802.16 communication system will be described.
Generally, an emergency service includes a Wireless Emergency Rescue Service (WERS) and a Wireless Emergency Alert Service (WEAS). Each of the WERS and the WEAS will be described.
The WERS is referred to as an MS-triggered Emergency Service (MS-triggered ES), and includes a rescue service that determines a location of an MS in an emergency situation, for example, a fire, a crime, etc. The WERS is generally triggered by an MS, which is the reason why the WERS is referred to as the MS-triggered ES. An example of the WERS includes a voice call service such as a 911 service.
The WEAS is referred to as a Base Station (BS)-triggered Emergency Service (BS-triggered ES), and includes a service supplying an emergency notification to an MS located in a specific geographical location. Examples of the emergency notification include a rainstorm warning, earthquake warning, a tidal storm warning, etc. The WEAS is generally triggered by a BS, which is the reason why the WEAS is referred to as the BS-triggered ES.
The conventional IEEE 802.16 communication system considers providing only the WEAS. The conventional IEEE 802.16 communication system proposes an operational method of a BS broadcasting information in a time duration in which the BS transmits an emergency service message to an MS using a Broadcast Control Pointer Information Element (IE) message included in a DownLink MAP (DL-MAP) message.
Table 1 shows a format of the Broadcast Control Pointer IE message
TABLE 1SizeSyntax(bit)NotesBroadcast_Control_Pointer_IE( ) {— Extended DIUC4Broadcast_Control_Pointer_IE( ) =0x0A Length4Length in bytes DCD_UCD Transmission Frame7The least significant bits of theframe number of the next DCDand/or UCD transmission. Skip Broadcast_System_Update1— If (Skip Broadcast_System_Update == 0)——{  Broadcast_System_Update_Type1Shows the type ofBroadcast_System_Update0: For MOB_NBR-ADV Update1: For Emergency ServicesMessage  Broadcast_System_Update7The least significant bits of the_Transmission _Frameframe number of the nextBroadcast_System_Updatetransmission. }}
In Table 1, an Extended Downlink Interval Usage Code (DIUC) represents a code used for identifying an IE message included in a DL-MAP message, a code used for identifying a Broadcast Control Pointer IE message is ‘0x0A’, a Length represents a length of the Broadcast Control Pointer IE message, a Downlink Channel Descriptor (DCD)_Uplink Channel Descriptor (UCD) Transmission Frame is used for representing a frame in which a DCD message and a UCD message are to be transmitted. Here, a value written in the DCD_UCD Transmission Frame represents a Least Significant Bit (LSB) of a frame number in which the next DCD and UCD messages are to be transmitted.
A time duration in which one of a Neighbor Advertisement (MOB_NBR-ADV) message and an emergency message will be transmitted uses the Broadcast Control Pointer IE message. In Table 1, a Skip Broadcast_System_Update represents whether information on the time duration in which one of the MOB_NBR-ADV message and the emergency message will be transmitted is omitted. For example, when a value of the Broadcast_System_Update is ‘0’, the Broadcast_System_Update represents that one of the information on the time duration in which one of the MOB_NBR-ADV message and the emergency message will be transmitted is not omitted.
When the Broadcast_System_Update represents that one of the information on the time duration in which one of the MOB_NBR-ADV message and the emergency message will be transmitted is not omitted, a Broadcast_System_Update_Type and a Broadcast_System_Update_Transmission_Frame are included in the Broadcast Control Pointer IE message. Here, the Broadcast_System_Update_Type represents which one of the MOB_NBR-ADV message and the emergency message will be transmitted, and the Broadcast_System_Update_Transmission_Frame represents a time duration in which a message represented by the Broadcast_System_Update_Type will be transmitted. For example, when a value of the Broadcast_System_Update_Type is ‘0’, the Broadcast_System_Update_Type represents that the MOB_NBR-ADV message will be transmitted, and when a value of the Broadcast_System_Update_Type is ‘1’, the Broadcast_System_Update_Type represents that the emergency message will be transmitted. The Broadcast_System_Update_Transmission_Frame represents an LSB of a frame number in which a message corresponding to a value of the Broadcast_System_Update_Type will be transmitted.
Generally, the Broadcast Control Pointer IE message is used for previously broadcasting a time duration in which a UCD message, a DCD message, a MOB_NBR-ADV message, and an emergency message are transmitted, when an MS in one of an idle mode and a sleep mode is not able to be supplied with a service from a BS in a pre-negotiated period. An MS that receives the Broadcast Control Pointer IE message may receive a corresponding message by waking-up at a start timing point of a corresponding time duration represented by the Broadcast Control Pointer IE message or may restart a service with a BS.
As described above, the conventional IEEE 802.16 communication system only defines an operation in which information on a timing point at which an emergency service message will be transmitted using a Broadcast Control Pointer IE message. That is, the conventional IEEE 802.16 communication system does not consider a specific method for providing an emergency service except for the Broadcast Control Pointer IE message. Thus, there is a need for a method for providing an emergency service in the conventional IEEE 802.16 communication system.